1. Field of the Invention
This invention relates to an engine, and more particularly to a rotary engine that includes a plurality of vanes, which are rotatable by compressed gas injected thereon.
2. Description of the Related Art
Referring to FIG. 1, a conventional rotary engine 1 includes an outer shell 11, a rotor 12, an output shaft 13, and two spark plugs 14.
The outer shell 11 includes a shell body 111 having an accommodating space 114, and a pair of intake and exhaust ports 112, 113 formed in the shell body 111 and in fluid communication with the accommodating space 114. The rotor 12 is rotatable within the accommodating space 114 in the outer shell 11, and has a generally triangular cross-section. The output shaft 13 extends into the shell body 111 of the outer shell 11 and the rotor 12, and is rotatable relative to the outer shell 11.
When the rotor 12 rotates in the accommodating space 114, three gas chambers 115 are defined between the rotor 12 and the shell body 111. During one revolution of the rotor 12, one working cycle of four strokes including intake, compression, combustion, and exhaust takes place within each of the gas chambers 115. Hence, power is outputted via the output shaft 13.
The aforesaid conventional rotary engine 1 suffers from the following disadvantages:    (1) Only three working cycles are completed respectively within the gas chambers 115 per one revolution of the rotor 12. Hence, the power output of the rotary engine 1 is limited.    (2) Since the rotor 12 rotates about an axis offset from the central axis of the output shaft 13, substantial vibrations occur during rotation of the rotor 12. As a result, running of the engine 1 is unstable.